# Anti-Lenz Supercurrents in Superconducting Spin Valves

## TL;DR

This paper investigates anomalous supercurrents in superconducting spin valves, revealing an inverted hysteresis loop in the magnetization of the Nb layer, challenging conventional understanding of superconductor/ferromagnet interactions.

## Contribution

It reports the discovery of anti-Lenz supercurrents in superconducting spin valves, demonstrating an inverted hysteresis behavior contrary to traditional expectations.

## Key findings

- Inverted hysteresis loop observed in superconducting Nb layers.
- Supercurrents exhibit behavior opposite to Lenz's rule.
- Magnetization strongly influenced by Nb layer thickness and temperature.

## Abstract

Here, we present a study on Si(111)/\-Ta($150$\AA )/\-IrMn($150$\AA )/\-NiFe($50$\AA )/\-Nb($x$)/\-NiFe($50$\AA )/\-Ta($50$\AA ) and Si(111)/\-Ta($150$\AA )/\-NiFe($50$\AA )/\-Nb($x$)/\-NiFe($50$\AA )/\-IrMn($150$\AA )/\-Ta($50$\AA ) spin-valves with $x=100$ to $500$\AA . For both sample families, above a specific critical thickness of the Nb-layer and below $T_c$, the superconducting Nb-layer contributes strongly to the magnetization. These systems show an anomalous hysteresis loop in the magnetization of the superconducting layer; the hysteresis loop is similar to what is generally expected from hard superconductors and many superconductor/ferromagnet hybrid systems, but the direction of the hysteresis loop is inverted, compared to what is generally observed (paramagnetic for up sweeping fields and diamagnetic for down sweeping fields). This means that the respective samples exhibit a magnetization, which is contrary to what should be expected from the Lenz' rule.